And so it came to pass in this, my 3rd winter of discontent, that I was pulling a 24-foot travel trailer to Gimli, Manitoba. I was feeling good that morning, having snagged a fortunate dispatch to Manitoba, which I had been trying to accomplish, being of somewhat dubious value, but marking incursions into Canada for me in all provinces from QC to BC. Adventure Dodge was humming out a steady 100 kph around Winnipeg's ring road, and I was savoring my morning coffee, looking forward to dropping the trailer in about another hour, then highballing it home. All of a sudden, the engine speed flared, the cruise control disengaged, and the truck commenced slowing down.
Oh, bother.
I've been through this before; the dreaded 5th gear nut in the NV4500 has departed the shaft, taking 5th gear with it. OK, so I have another neutral, but I'm prepared, because the GearVendors overdrive gives me another gear that is within 5% of the late, lamented 5th gear, so I can complete the run without being a rolling chicane, then I'll figure out how to get home, all of 1100 miles away. Shoved the shifter into 4th, switched on the overdrive, and torque once again flows to the rear wheels. Yay! I don't have to walk home, at least not immediately. But the next few miles induce a cold sweat on my brow and a knot in my stomach as I listen to noises from the transmission akin to gravel tumbling in a clothes dryer. It's probably just the split thrust washer rubbing against 5th driving gear, and will drop out if I slow down or stop. So I stopped, shut the engine down, then restarted, and VOILA!, no more gravel-in-a-dryer noise. The rest of the run to Gimli was nice and easy, the Manitoba roads being flat and straight, and the people at the RV dealer were friendly and completed the trailer check-in without hassle.
So now, getting home. What to do? Being without double-overdrive is going to slow me down, so the trip will take longer. Or will the thing even go that far? Should I just rent a U-Haul van and dolly in the first major town I come to, and tow it home? Nahh! The last time I lost 5th, I ran 3000 miles, 1200 of it towing a heavy trailer. Do the trip in stages. If you can get to Winnipeg, maybe you can find the rental. OK, made the run to Winnipeg with no sickening noises from the trans, so try to make Grand Forks, ND and get the rental there. OK, made the run the Grand Forks, and no noises, and the transmission is shifting fine, so just go for the whole enchilada and drive this puppy home!
From that point on, the trip home relaxed into a somewhat slow winter tour of northern MN and the UP of MI on secondary roads. US 2 is now my friend. Adventure Dodge ran steadily all the way, actually returning 21 mpg on winter fuel. I guess going slow does help fuel economy, even if you aren't in the most economical gear. Heck, the Dodge felt so good when I got home, I took another trailer into southern ON, doing another 800 miles. It finally came time to take the transmission apart and see what the problem(s) is/are.
The first picture is the output shaft with the pieces hanging on it exactly as I removed the tailshaft adapter. The pieces from left to right are the retaining nut, the Belleville washer, the thrust washer retaining ring, and the 5th gear pinion.
The second picture is a closeup of the split retaining nut that was Chrysler's design solution to the 5th gear nut problem. It is the culprit for this failure because the slot machined into the cross-section of the nut was a stress riser, allowing a crack to form and progress through the rest of the section, thereby losing clamp load on the shaft and its eventual ejection off the back off the threads.
Oh, bother.
I've been through this before; the dreaded 5th gear nut in the NV4500 has departed the shaft, taking 5th gear with it. OK, so I have another neutral, but I'm prepared, because the GearVendors overdrive gives me another gear that is within 5% of the late, lamented 5th gear, so I can complete the run without being a rolling chicane, then I'll figure out how to get home, all of 1100 miles away. Shoved the shifter into 4th, switched on the overdrive, and torque once again flows to the rear wheels. Yay! I don't have to walk home, at least not immediately. But the next few miles induce a cold sweat on my brow and a knot in my stomach as I listen to noises from the transmission akin to gravel tumbling in a clothes dryer. It's probably just the split thrust washer rubbing against 5th driving gear, and will drop out if I slow down or stop. So I stopped, shut the engine down, then restarted, and VOILA!, no more gravel-in-a-dryer noise. The rest of the run to Gimli was nice and easy, the Manitoba roads being flat and straight, and the people at the RV dealer were friendly and completed the trailer check-in without hassle.
So now, getting home. What to do? Being without double-overdrive is going to slow me down, so the trip will take longer. Or will the thing even go that far? Should I just rent a U-Haul van and dolly in the first major town I come to, and tow it home? Nahh! The last time I lost 5th, I ran 3000 miles, 1200 of it towing a heavy trailer. Do the trip in stages. If you can get to Winnipeg, maybe you can find the rental. OK, made the run to Winnipeg with no sickening noises from the trans, so try to make Grand Forks, ND and get the rental there. OK, made the run the Grand Forks, and no noises, and the transmission is shifting fine, so just go for the whole enchilada and drive this puppy home!
From that point on, the trip home relaxed into a somewhat slow winter tour of northern MN and the UP of MI on secondary roads. US 2 is now my friend. Adventure Dodge ran steadily all the way, actually returning 21 mpg on winter fuel. I guess going slow does help fuel economy, even if you aren't in the most economical gear. Heck, the Dodge felt so good when I got home, I took another trailer into southern ON, doing another 800 miles. It finally came time to take the transmission apart and see what the problem(s) is/are.
The first picture is the output shaft with the pieces hanging on it exactly as I removed the tailshaft adapter. The pieces from left to right are the retaining nut, the Belleville washer, the thrust washer retaining ring, and the 5th gear pinion.
The second picture is a closeup of the split retaining nut that was Chrysler's design solution to the 5th gear nut problem. It is the culprit for this failure because the slot machined into the cross-section of the nut was a stress riser, allowing a crack to form and progress through the rest of the section, thereby losing clamp load on the shaft and its eventual ejection off the back off the threads.
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